Restore the ability to continue booting after legacy image overwrite

Before new uImage code was merged, bootm code allowed for the kernel image to
get overwritten during decompresion. new uImage introduced a check for image
overwrites and refused to boot the image that got overwritten. This patch
restores the old behavior. It also adds a warning when the image overwriten is
a multi-image file, because in such case accessing componentes other than the
first one will fail.

Signed-off-by: Marian Balakowicz <m8@semihalf.com>
diff --git a/include/image.h b/include/image.h
index c1a6cbb..60fdb2b 100644
--- a/include/image.h
+++ b/include/image.h
@@ -197,7 +197,8 @@
 	 * then boot_get_ramdisk() and get_fdt() will attempt to get
 	 * data from second and third component accordingly.
 	 */
-	image_header_t	*legacy_hdr_os;
+	image_header_t	*legacy_hdr_os;		/* image header pointer */
+	image_header_t	legacy_hdr_os_copy;	/* header copy */
 	ulong		legacy_hdr_valid;
 
 #if defined(CONFIG_FIT)